1 /*
   2  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/vmSymbols.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc_implementation/shared/collectorCounters.hpp"
  31 #include "gc_implementation/shared/vmGCOperations.hpp"
  32 #include "gc_interface/collectedHeap.inline.hpp"
  33 #include "memory/compactPermGen.hpp"
  34 #include "memory/filemap.hpp"
  35 #include "memory/gcLocker.inline.hpp"
  36 #include "memory/genCollectedHeap.hpp"
  37 #include "memory/genOopClosures.inline.hpp"
  38 #include "memory/generation.inline.hpp"
  39 #include "memory/generationSpec.hpp"
  40 #include "memory/permGen.hpp"
  41 #include "memory/resourceArea.hpp"
  42 #include "memory/sharedHeap.hpp"
  43 #include "memory/space.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "oops/oop.inline2.hpp"
  46 #include "runtime/aprofiler.hpp"
  47 #include "runtime/biasedLocking.hpp"
  48 #include "runtime/fprofiler.hpp"
  49 #include "runtime/handles.hpp"
  50 #include "runtime/handles.inline.hpp"
  51 #include "runtime/java.hpp"
  52 #include "runtime/vmThread.hpp"
  53 #include "services/memoryService.hpp"
  54 #include "utilities/vmError.hpp"
  55 #include "utilities/workgroup.hpp"
  56 #ifndef SERIALGC
  57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
  59 #endif
  60 
  61 GenCollectedHeap* GenCollectedHeap::_gch;
  62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
  63 
  64 // The set of potentially parallel tasks in strong root scanning.
  65 enum GCH_process_strong_roots_tasks {
  66   // We probably want to parallelize both of these internally, but for now...
  67   GCH_PS_younger_gens,
  68   // Leave this one last.
  69   GCH_PS_NumElements
  70 };
  71 
  72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
  73   SharedHeap(policy),
  74   _gen_policy(policy),
  75   _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
  76   _full_collections_completed(0)
  77 {
  78   if (_gen_process_strong_tasks == NULL ||
  79       !_gen_process_strong_tasks->valid()) {
  80     vm_exit_during_initialization("Failed necessary allocation.");
  81   }
  82   assert(policy != NULL, "Sanity check");
  83   _preloading_shared_classes = false;
  84 }
  85 
  86 jint GenCollectedHeap::initialize() {
  87   CollectedHeap::pre_initialize();
  88 
  89   int i;
  90   _n_gens = gen_policy()->number_of_generations();
  91 
  92   // While there are no constraints in the GC code that HeapWordSize
  93   // be any particular value, there are multiple other areas in the
  94   // system which believe this to be true (e.g. oop->object_size in some
  95   // cases incorrectly returns the size in wordSize units rather than
  96   // HeapWordSize).
  97   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
  98 
  99   // The heap must be at least as aligned as generations.
 100   size_t alignment = Generation::GenGrain;
 101 
 102   _gen_specs = gen_policy()->generations();
 103   PermanentGenerationSpec *perm_gen_spec =
 104                                 collector_policy()->permanent_generation();
 105 
 106   // Make sure the sizes are all aligned.
 107   for (i = 0; i < _n_gens; i++) {
 108     _gen_specs[i]->align(alignment);
 109   }
 110   perm_gen_spec->align(alignment);
 111 
 112   // If we are dumping the heap, then allocate a wasted block of address
 113   // space in order to push the heap to a lower address.  This extra
 114   // address range allows for other (or larger) libraries to be loaded
 115   // without them occupying the space required for the shared spaces.
 116 
 117   if (DumpSharedSpaces) {
 118     uintx reserved = 0;
 119     uintx block_size = 64*1024*1024;
 120     while (reserved < SharedDummyBlockSize) {
 121       char* dummy = os::reserve_memory(block_size);
 122       reserved += block_size;
 123     }
 124   }
 125 
 126   // Allocate space for the heap.
 127 
 128   char* heap_address;
 129   size_t total_reserved = 0;
 130   int n_covered_regions = 0;
 131   ReservedSpace heap_rs(0);
 132 
 133   heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
 134                           &n_covered_regions, &heap_rs);
 135 
 136   if (UseSharedSpaces) {
 137     if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {
 138       if (heap_rs.is_reserved()) {
 139         heap_rs.release();
 140       }
 141       FileMapInfo* mapinfo = FileMapInfo::current_info();
 142       mapinfo->fail_continue("Unable to reserve shared region.");
 143       allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,
 144                &heap_rs);
 145     }
 146   }
 147 
 148   if (!heap_rs.is_reserved()) {
 149     vm_shutdown_during_initialization(
 150       "Could not reserve enough space for object heap");
 151     return JNI_ENOMEM;
 152   }
 153 
 154   _reserved = MemRegion((HeapWord*)heap_rs.base(),
 155                         (HeapWord*)(heap_rs.base() + heap_rs.size()));
 156 
 157   // It is important to do this in a way such that concurrent readers can't
 158   // temporarily think somethings in the heap.  (Seen this happen in asserts.)
 159   _reserved.set_word_size(0);
 160   _reserved.set_start((HeapWord*)heap_rs.base());
 161   size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()
 162                                            - perm_gen_spec->misc_code_size();
 163   _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
 164 
 165   _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
 166   set_barrier_set(rem_set()->bs());
 167 
 168   _gch = this;
 169 
 170   for (i = 0; i < _n_gens; i++) {
 171     ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),
 172                                               UseSharedSpaces, UseSharedSpaces);
 173     _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
 174     heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
 175   }
 176   _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
 177 
 178   clear_incremental_collection_failed();
 179 
 180 #ifndef SERIALGC
 181   // If we are running CMS, create the collector responsible
 182   // for collecting the CMS generations.
 183   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 184     bool success = create_cms_collector();
 185     if (!success) return JNI_ENOMEM;
 186   }
 187 #endif // SERIALGC
 188 
 189   return JNI_OK;
 190 }
 191 
 192 
 193 char* GenCollectedHeap::allocate(size_t alignment,
 194                                  PermanentGenerationSpec* perm_gen_spec,
 195                                  size_t* _total_reserved,
 196                                  int* _n_covered_regions,
 197                                  ReservedSpace* heap_rs){
 198   const char overflow_msg[] = "The size of the object heap + VM data exceeds "
 199     "the maximum representable size";
 200 
 201   // Now figure out the total size.
 202   size_t total_reserved = 0;
 203   int n_covered_regions = 0;
 204   const size_t pageSize = UseLargePages ?
 205       os::large_page_size() : os::vm_page_size();
 206 
 207   for (int i = 0; i < _n_gens; i++) {
 208     total_reserved += _gen_specs[i]->max_size();
 209     if (total_reserved < _gen_specs[i]->max_size()) {
 210       vm_exit_during_initialization(overflow_msg);
 211     }
 212     n_covered_regions += _gen_specs[i]->n_covered_regions();
 213   }
 214   assert(total_reserved % pageSize == 0,
 215          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", pageSize="
 216                  SIZE_FORMAT, total_reserved, pageSize));
 217   total_reserved += perm_gen_spec->max_size();
 218   assert(total_reserved % pageSize == 0,
 219          err_msg("Perm size; total_reserved=" SIZE_FORMAT ", pageSize="
 220                  SIZE_FORMAT ", perm gen max=" SIZE_FORMAT, total_reserved,
 221                  pageSize, perm_gen_spec->max_size()));
 222 
 223   if (total_reserved < perm_gen_spec->max_size()) {
 224     vm_exit_during_initialization(overflow_msg);
 225   }
 226   n_covered_regions += perm_gen_spec->n_covered_regions();
 227 
 228   // Add the size of the data area which shares the same reserved area
 229   // as the heap, but which is not actually part of the heap.
 230   size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();
 231 
 232   total_reserved += s;
 233   if (total_reserved < s) {
 234     vm_exit_during_initialization(overflow_msg);
 235   }
 236 
 237   if (UseLargePages) {
 238     assert(total_reserved != 0, "total_reserved cannot be 0");
 239     total_reserved = round_to(total_reserved, os::large_page_size());
 240     if (total_reserved < os::large_page_size()) {
 241       vm_exit_during_initialization(overflow_msg);
 242     }
 243   }
 244 
 245   // Calculate the address at which the heap must reside in order for
 246   // the shared data to be at the required address.
 247 
 248   char* heap_address;
 249   if (UseSharedSpaces) {
 250 
 251     // Calculate the address of the first word beyond the heap.
 252     FileMapInfo* mapinfo = FileMapInfo::current_info();
 253     int lr = CompactingPermGenGen::n_regions - 1;
 254     size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);
 255     heap_address = mapinfo->region_base(lr) + capacity;
 256 
 257     // Calculate the address of the first word of the heap.
 258     heap_address -= total_reserved;
 259   } else {
 260     heap_address = NULL;  // any address will do.
 261     if (UseCompressedOops) {
 262       heap_address = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
 263       *_total_reserved = total_reserved;
 264       *_n_covered_regions = n_covered_regions;
 265       *heap_rs = ReservedHeapSpace(total_reserved, alignment,
 266                                    UseLargePages, heap_address);
 267 
 268       if (heap_address != NULL && !heap_rs->is_reserved()) {
 269         // Failed to reserve at specified address - the requested memory
 270         // region is taken already, for example, by 'java' launcher.
 271         // Try again to reserver heap higher.
 272         heap_address = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
 273         *heap_rs = ReservedHeapSpace(total_reserved, alignment,
 274                                      UseLargePages, heap_address);
 275 
 276         if (heap_address != NULL && !heap_rs->is_reserved()) {
 277           // Failed to reserve at specified address again - give up.
 278           heap_address = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
 279           assert(heap_address == NULL, "");
 280           *heap_rs = ReservedHeapSpace(total_reserved, alignment,
 281                                        UseLargePages, heap_address);
 282         }
 283       }
 284       return heap_address;
 285     }
 286   }
 287 
 288   *_total_reserved = total_reserved;
 289   *_n_covered_regions = n_covered_regions;
 290   *heap_rs = ReservedHeapSpace(total_reserved, alignment,
 291                                UseLargePages, heap_address);
 292 
 293   return heap_address;
 294 }
 295 
 296 
 297 void GenCollectedHeap::post_initialize() {
 298   SharedHeap::post_initialize();
 299   TwoGenerationCollectorPolicy *policy =
 300     (TwoGenerationCollectorPolicy *)collector_policy();
 301   guarantee(policy->is_two_generation_policy(), "Illegal policy type");
 302   DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
 303   assert(def_new_gen->kind() == Generation::DefNew ||
 304          def_new_gen->kind() == Generation::ParNew ||
 305          def_new_gen->kind() == Generation::ASParNew,
 306          "Wrong generation kind");
 307 
 308   Generation* old_gen = get_gen(1);
 309   assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
 310          old_gen->kind() == Generation::ASConcurrentMarkSweep ||
 311          old_gen->kind() == Generation::MarkSweepCompact,
 312     "Wrong generation kind");
 313 
 314   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 315                                  old_gen->capacity(),
 316                                  def_new_gen->from()->capacity());
 317   policy->initialize_gc_policy_counters();
 318 }
 319 
 320 void GenCollectedHeap::ref_processing_init() {
 321   SharedHeap::ref_processing_init();
 322   for (int i = 0; i < _n_gens; i++) {
 323     _gens[i]->ref_processor_init();
 324   }
 325 }
 326 
 327 size_t GenCollectedHeap::capacity() const {
 328   size_t res = 0;
 329   for (int i = 0; i < _n_gens; i++) {
 330     res += _gens[i]->capacity();
 331   }
 332   return res;
 333 }
 334 
 335 size_t GenCollectedHeap::used() const {
 336   size_t res = 0;
 337   for (int i = 0; i < _n_gens; i++) {
 338     res += _gens[i]->used();
 339   }
 340   return res;
 341 }
 342 
 343 // Save the "used_region" for generations level and lower,
 344 // and, if perm is true, for perm gen.
 345 void GenCollectedHeap::save_used_regions(int level, bool perm) {
 346   assert(level < _n_gens, "Illegal level parameter");
 347   for (int i = level; i >= 0; i--) {
 348     _gens[i]->save_used_region();
 349   }
 350   if (perm) {
 351     perm_gen()->save_used_region();
 352   }
 353 }
 354 
 355 size_t GenCollectedHeap::max_capacity() const {
 356   size_t res = 0;
 357   for (int i = 0; i < _n_gens; i++) {
 358     res += _gens[i]->max_capacity();
 359   }
 360   return res;
 361 }
 362 
 363 // Update the _full_collections_completed counter
 364 // at the end of a stop-world full GC.
 365 unsigned int GenCollectedHeap::update_full_collections_completed() {
 366   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 367   assert(_full_collections_completed <= _total_full_collections,
 368          "Can't complete more collections than were started");
 369   _full_collections_completed = _total_full_collections;
 370   ml.notify_all();
 371   return _full_collections_completed;
 372 }
 373 
 374 // Update the _full_collections_completed counter, as appropriate,
 375 // at the end of a concurrent GC cycle. Note the conditional update
 376 // below to allow this method to be called by a concurrent collector
 377 // without synchronizing in any manner with the VM thread (which
 378 // may already have initiated a STW full collection "concurrently").
 379 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 380   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 381   assert((_full_collections_completed <= _total_full_collections) &&
 382          (count <= _total_full_collections),
 383          "Can't complete more collections than were started");
 384   if (count > _full_collections_completed) {
 385     _full_collections_completed = count;
 386     ml.notify_all();
 387   }
 388   return _full_collections_completed;
 389 }
 390 
 391 
 392 #ifndef PRODUCT
 393 // Override of memory state checking method in CollectedHeap:
 394 // Some collectors (CMS for example) can't have badHeapWordVal written
 395 // in the first two words of an object. (For instance , in the case of
 396 // CMS these words hold state used to synchronize between certain
 397 // (concurrent) GC steps and direct allocating mutators.)
 398 // The skip_header_HeapWords() method below, allows us to skip
 399 // over the requisite number of HeapWord's. Note that (for
 400 // generational collectors) this means that those many words are
 401 // skipped in each object, irrespective of the generation in which
 402 // that object lives. The resultant loss of precision seems to be
 403 // harmless and the pain of avoiding that imprecision appears somewhat
 404 // higher than we are prepared to pay for such rudimentary debugging
 405 // support.
 406 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 407                                                          size_t size) {
 408   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 409     // We are asked to check a size in HeapWords,
 410     // but the memory is mangled in juint words.
 411     juint* start = (juint*) (addr + skip_header_HeapWords());
 412     juint* end   = (juint*) (addr + size);
 413     for (juint* slot = start; slot < end; slot += 1) {
 414       assert(*slot == badHeapWordVal,
 415              "Found non badHeapWordValue in pre-allocation check");
 416     }
 417   }
 418 }
 419 #endif
 420 
 421 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 422                                                bool is_tlab,
 423                                                bool first_only) {
 424   HeapWord* res;
 425   for (int i = 0; i < _n_gens; i++) {
 426     if (_gens[i]->should_allocate(size, is_tlab)) {
 427       res = _gens[i]->allocate(size, is_tlab);
 428       if (res != NULL) return res;
 429       else if (first_only) break;
 430     }
 431   }
 432   // Otherwise...
 433   return NULL;
 434 }
 435 
 436 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 437                                          bool* gc_overhead_limit_was_exceeded) {
 438   return collector_policy()->mem_allocate_work(size,
 439                                                false /* is_tlab */,
 440                                                gc_overhead_limit_was_exceeded);
 441 }
 442 
 443 bool GenCollectedHeap::must_clear_all_soft_refs() {
 444   return _gc_cause == GCCause::_last_ditch_collection;
 445 }
 446 
 447 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 448   return UseConcMarkSweepGC &&
 449          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 450           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 451 }
 452 
 453 void GenCollectedHeap::do_collection(bool  full,
 454                                      bool   clear_all_soft_refs,
 455                                      size_t size,
 456                                      bool   is_tlab,
 457                                      int    max_level) {
 458   bool prepared_for_verification = false;
 459   ResourceMark rm;
 460   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 461 
 462   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 463   assert(my_thread->is_VM_thread() ||
 464          my_thread->is_ConcurrentGC_thread(),
 465          "incorrect thread type capability");
 466   assert(Heap_lock->is_locked(),
 467          "the requesting thread should have the Heap_lock");
 468   guarantee(!is_gc_active(), "collection is not reentrant");
 469   assert(max_level < n_gens(), "sanity check");
 470 
 471   if (GC_locker::check_active_before_gc()) {
 472     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 473   }
 474 
 475   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 476                           collector_policy()->should_clear_all_soft_refs();
 477 
 478   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 479 
 480   const size_t perm_prev_used = perm_gen()->used();
 481 
 482   print_heap_before_gc();
 483 
 484   {
 485     FlagSetting fl(_is_gc_active, true);
 486 
 487     bool complete = full && (max_level == (n_gens()-1));
 488     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 489     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 490     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 491     TraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, gclog_or_tty);
 492 
 493     gc_prologue(complete);
 494     increment_total_collections(complete);
 495 
 496     size_t gch_prev_used = used();
 497 
 498     int starting_level = 0;
 499     if (full) {
 500       // Search for the oldest generation which will collect all younger
 501       // generations, and start collection loop there.
 502       for (int i = max_level; i >= 0; i--) {
 503         if (_gens[i]->full_collects_younger_generations()) {
 504           starting_level = i;
 505           break;
 506         }
 507       }
 508     }
 509 
 510     bool must_restore_marks_for_biased_locking = false;
 511 
 512     int max_level_collected = starting_level;
 513     for (int i = starting_level; i <= max_level; i++) {
 514       if (_gens[i]->should_collect(full, size, is_tlab)) {
 515         if (i == n_gens() - 1) {  // a major collection is to happen
 516           if (!complete) {
 517             // The full_collections increment was missed above.
 518             increment_total_full_collections();
 519           }
 520           pre_full_gc_dump();    // do any pre full gc dumps
 521         }
 522         // Timer for individual generations. Last argument is false: no CR
 523         TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);
 524         TraceCollectorStats tcs(_gens[i]->counters());
 525         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 526 
 527         size_t prev_used = _gens[i]->used();
 528         _gens[i]->stat_record()->invocations++;
 529         _gens[i]->stat_record()->accumulated_time.start();
 530 
 531         // Must be done anew before each collection because
 532         // a previous collection will do mangling and will
 533         // change top of some spaces.
 534         record_gen_tops_before_GC();
 535 
 536         if (PrintGC && Verbose) {
 537           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 538                      i,
 539                      _gens[i]->stat_record()->invocations,
 540                      size*HeapWordSize);
 541         }
 542 
 543         if (VerifyBeforeGC && i >= VerifyGCLevel &&
 544             total_collections() >= VerifyGCStartAt) {
 545           HandleMark hm;  // Discard invalid handles created during verification
 546           if (!prepared_for_verification) {
 547             prepare_for_verify();
 548             prepared_for_verification = true;
 549           }
 550           gclog_or_tty->print(" VerifyBeforeGC:");
 551           Universe::verify(true);
 552         }
 553         COMPILER2_PRESENT(DerivedPointerTable::clear());
 554 
 555         if (!must_restore_marks_for_biased_locking &&
 556             _gens[i]->performs_in_place_marking()) {
 557           // We perform this mark word preservation work lazily
 558           // because it's only at this point that we know whether we
 559           // absolutely have to do it; we want to avoid doing it for
 560           // scavenge-only collections where it's unnecessary
 561           must_restore_marks_for_biased_locking = true;
 562           BiasedLocking::preserve_marks();
 563         }
 564 
 565         // Do collection work
 566         {
 567           // Note on ref discovery: For what appear to be historical reasons,
 568           // GCH enables and disabled (by enqueing) refs discovery.
 569           // In the future this should be moved into the generation's
 570           // collect method so that ref discovery and enqueueing concerns
 571           // are local to a generation. The collect method could return
 572           // an appropriate indication in the case that notification on
 573           // the ref lock was needed. This will make the treatment of
 574           // weak refs more uniform (and indeed remove such concerns
 575           // from GCH). XXX
 576 
 577           HandleMark hm;  // Discard invalid handles created during gc
 578           save_marks();   // save marks for all gens
 579           // We want to discover references, but not process them yet.
 580           // This mode is disabled in process_discovered_references if the
 581           // generation does some collection work, or in
 582           // enqueue_discovered_references if the generation returns
 583           // without doing any work.
 584           ReferenceProcessor* rp = _gens[i]->ref_processor();
 585           // If the discovery of ("weak") refs in this generation is
 586           // atomic wrt other collectors in this configuration, we
 587           // are guaranteed to have empty discovered ref lists.
 588           if (rp->discovery_is_atomic()) {
 589             rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 590             rp->setup_policy(do_clear_all_soft_refs);
 591           } else {
 592             // collect() below will enable discovery as appropriate
 593           }
 594           _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
 595           if (!rp->enqueuing_is_done()) {
 596             rp->enqueue_discovered_references();
 597           } else {
 598             rp->set_enqueuing_is_done(false);
 599           }
 600           rp->verify_no_references_recorded();
 601         }
 602         max_level_collected = i;
 603 
 604         // Determine if allocation request was met.
 605         if (size > 0) {
 606           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
 607             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
 608               size = 0;
 609             }
 610           }
 611         }
 612 
 613         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 614 
 615         _gens[i]->stat_record()->accumulated_time.stop();
 616 
 617         update_gc_stats(i, full);
 618 
 619         if (VerifyAfterGC && i >= VerifyGCLevel &&
 620             total_collections() >= VerifyGCStartAt) {
 621           HandleMark hm;  // Discard invalid handles created during verification
 622           gclog_or_tty->print(" VerifyAfterGC:");
 623           Universe::verify(false);
 624         }
 625 
 626         if (PrintGCDetails) {
 627           gclog_or_tty->print(":");
 628           _gens[i]->print_heap_change(prev_used);
 629         }
 630       }
 631     }
 632 
 633     // Update "complete" boolean wrt what actually transpired --
 634     // for instance, a promotion failure could have led to
 635     // a whole heap collection.
 636     complete = complete || (max_level_collected == n_gens() - 1);
 637 
 638     if (complete) { // We did a "major" collection
 639       post_full_gc_dump();   // do any post full gc dumps
 640     }
 641 
 642     if (PrintGCDetails) {
 643       print_heap_change(gch_prev_used);
 644 
 645       // Print perm gen info for full GC with PrintGCDetails flag.
 646       if (complete) {
 647         print_perm_heap_change(perm_prev_used);
 648       }
 649     }
 650 
 651     for (int j = max_level_collected; j >= 0; j -= 1) {
 652       // Adjust generation sizes.
 653       _gens[j]->compute_new_size();
 654     }
 655 
 656     if (complete) {
 657       // Ask the permanent generation to adjust size for full collections
 658       perm()->compute_new_size();
 659       update_full_collections_completed();
 660     }
 661 
 662     // Track memory usage and detect low memory after GC finishes
 663     MemoryService::track_memory_usage();
 664 
 665     gc_epilogue(complete);
 666 
 667     if (must_restore_marks_for_biased_locking) {
 668       BiasedLocking::restore_marks();
 669     }
 670   }
 671 
 672   AdaptiveSizePolicy* sp = gen_policy()->size_policy();
 673   AdaptiveSizePolicyOutput(sp, total_collections());
 674 
 675   print_heap_after_gc();
 676 
 677 #ifdef TRACESPINNING
 678   ParallelTaskTerminator::print_termination_counts();
 679 #endif
 680 
 681   if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
 682     tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
 683     vm_exit(-1);
 684   }
 685 }
 686 
 687 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 688   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 689 }
 690 
 691 void GenCollectedHeap::set_par_threads(uint t) {
 692   SharedHeap::set_par_threads(t);
 693   _gen_process_strong_tasks->set_n_threads(t);
 694 }
 695 
 696 void GenCollectedHeap::
 697 gen_process_strong_roots(int level,
 698                          bool younger_gens_as_roots,
 699                          bool activate_scope,
 700                          bool collecting_perm_gen,
 701                          SharedHeap::ScanningOption so,
 702                          OopsInGenClosure* not_older_gens,
 703                          bool do_code_roots,
 704                          OopsInGenClosure* older_gens) {
 705   // General strong roots.
 706 
 707   if (!do_code_roots) {
 708     SharedHeap::process_strong_roots(activate_scope, collecting_perm_gen, so,
 709                                      not_older_gens, NULL, older_gens);
 710   } else {
 711     bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active());
 712     CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking);
 713     SharedHeap::process_strong_roots(activate_scope, collecting_perm_gen, so,
 714                                      not_older_gens, &code_roots, older_gens);
 715   }
 716 
 717   if (younger_gens_as_roots) {
 718     if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 719       for (int i = 0; i < level; i++) {
 720         not_older_gens->set_generation(_gens[i]);
 721         _gens[i]->oop_iterate(not_older_gens);
 722       }
 723       not_older_gens->reset_generation();
 724     }
 725   }
 726   // When collection is parallel, all threads get to cooperate to do
 727   // older-gen scanning.
 728   for (int i = level+1; i < _n_gens; i++) {
 729     older_gens->set_generation(_gens[i]);
 730     rem_set()->younger_refs_iterate(_gens[i], older_gens);
 731     older_gens->reset_generation();
 732   }
 733 
 734   _gen_process_strong_tasks->all_tasks_completed();
 735 }
 736 
 737 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
 738                                               CodeBlobClosure* code_roots,
 739                                               OopClosure* non_root_closure) {
 740   SharedHeap::process_weak_roots(root_closure, code_roots, non_root_closure);
 741   // "Local" "weak" refs
 742   for (int i = 0; i < _n_gens; i++) {
 743     _gens[i]->ref_processor()->weak_oops_do(root_closure);
 744   }
 745 }
 746 
 747 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 748 void GenCollectedHeap::                                                 \
 749 oop_since_save_marks_iterate(int level,                                 \
 750                              OopClosureType* cur,                       \
 751                              OopClosureType* older) {                   \
 752   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
 753   for (int i = level+1; i < n_gens(); i++) {                            \
 754     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \
 755   }                                                                     \
 756   perm_gen()->oop_since_save_marks_iterate##nv_suffix(older);           \
 757 }
 758 
 759 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 760 
 761 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 762 
 763 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 764   for (int i = level; i < _n_gens; i++) {
 765     if (!_gens[i]->no_allocs_since_save_marks()) return false;
 766   }
 767   return perm_gen()->no_allocs_since_save_marks();
 768 }
 769 
 770 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 771   return _gens[0]->supports_inline_contig_alloc();
 772 }
 773 
 774 HeapWord** GenCollectedHeap::top_addr() const {
 775   return _gens[0]->top_addr();
 776 }
 777 
 778 HeapWord** GenCollectedHeap::end_addr() const {
 779   return _gens[0]->end_addr();
 780 }
 781 
 782 size_t GenCollectedHeap::unsafe_max_alloc() {
 783   return _gens[0]->unsafe_max_alloc_nogc();
 784 }
 785 
 786 // public collection interfaces
 787 
 788 void GenCollectedHeap::collect(GCCause::Cause cause) {
 789   if (should_do_concurrent_full_gc(cause)) {
 790 #ifndef SERIALGC
 791     // mostly concurrent full collection
 792     collect_mostly_concurrent(cause);
 793 #else  // SERIALGC
 794     ShouldNotReachHere();
 795 #endif // SERIALGC
 796   } else {
 797 #ifdef ASSERT
 798     if (cause == GCCause::_scavenge_alot) {
 799       // minor collection only
 800       collect(cause, 0);
 801     } else {
 802       // Stop-the-world full collection
 803       collect(cause, n_gens() - 1);
 804     }
 805 #else
 806     // Stop-the-world full collection
 807     collect(cause, n_gens() - 1);
 808 #endif
 809   }
 810 }
 811 
 812 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 813   // The caller doesn't have the Heap_lock
 814   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 815   MutexLocker ml(Heap_lock);
 816   collect_locked(cause, max_level);
 817 }
 818 
 819 // This interface assumes that it's being called by the
 820 // vm thread. It collects the heap assuming that the
 821 // heap lock is already held and that we are executing in
 822 // the context of the vm thread.
 823 void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
 824   assert(Thread::current()->is_VM_thread(), "Precondition#1");
 825   assert(Heap_lock->is_locked(), "Precondition#2");
 826   GCCauseSetter gcs(this, cause);
 827   switch (cause) {
 828     case GCCause::_heap_inspection:
 829     case GCCause::_heap_dump: {
 830       HandleMark hm;
 831       do_full_collection(false,         // don't clear all soft refs
 832                          n_gens() - 1);
 833       break;
 834     }
 835     default: // XXX FIX ME
 836       ShouldNotReachHere(); // Unexpected use of this function
 837   }
 838 }
 839 
 840 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 841   // The caller has the Heap_lock
 842   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 843   collect_locked(cause, n_gens() - 1);
 844 }
 845 
 846 // this is the private collection interface
 847 // The Heap_lock is expected to be held on entry.
 848 
 849 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 850   if (_preloading_shared_classes) {
 851     report_out_of_shared_space(SharedPermGen);
 852   }
 853   // Read the GC count while holding the Heap_lock
 854   unsigned int gc_count_before      = total_collections();
 855   unsigned int full_gc_count_before = total_full_collections();
 856   {
 857     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 858     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 859                          cause, max_level);
 860     VMThread::execute(&op);
 861   }
 862 }
 863 
 864 #ifndef SERIALGC
 865 bool GenCollectedHeap::create_cms_collector() {
 866 
 867   assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
 868          (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
 869          _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
 870          "Unexpected generation kinds");
 871   // Skip two header words in the block content verification
 872   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 873   CMSCollector* collector = new CMSCollector(
 874     (ConcurrentMarkSweepGeneration*)_gens[1],
 875     (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
 876     _rem_set->as_CardTableRS(),
 877     (ConcurrentMarkSweepPolicy*) collector_policy());
 878 
 879   if (collector == NULL || !collector->completed_initialization()) {
 880     if (collector) {
 881       delete collector;  // Be nice in embedded situation
 882     }
 883     vm_shutdown_during_initialization("Could not create CMS collector");
 884     return false;
 885   }
 886   return true;  // success
 887 }
 888 
 889 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 890   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 891 
 892   MutexLocker ml(Heap_lock);
 893   // Read the GC counts while holding the Heap_lock
 894   unsigned int full_gc_count_before = total_full_collections();
 895   unsigned int gc_count_before      = total_collections();
 896   {
 897     MutexUnlocker mu(Heap_lock);
 898     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 899     VMThread::execute(&op);
 900   }
 901 }
 902 #endif // SERIALGC
 903 
 904 
 905 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 906                                           int max_level) {
 907   int local_max_level;
 908   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 909       gc_cause() == GCCause::_gc_locker) {
 910     local_max_level = 0;
 911   } else {
 912     local_max_level = max_level;
 913   }
 914 
 915   do_collection(true                 /* full */,
 916                 clear_all_soft_refs  /* clear_all_soft_refs */,
 917                 0                    /* size */,
 918                 false                /* is_tlab */,
 919                 local_max_level      /* max_level */);
 920   // Hack XXX FIX ME !!!
 921   // A scavenge may not have been attempted, or may have
 922   // been attempted and failed, because the old gen was too full
 923   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 924       incremental_collection_will_fail(false /* don't consult_young */)) {
 925     if (PrintGCDetails) {
 926       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 927                              "because scavenge failed");
 928     }
 929     // This time allow the old gen to be collected as well
 930     do_collection(true                 /* full */,
 931                   clear_all_soft_refs  /* clear_all_soft_refs */,
 932                   0                    /* size */,
 933                   false                /* is_tlab */,
 934                   n_gens() - 1         /* max_level */);
 935   }
 936 }
 937 
 938 bool GenCollectedHeap::is_in_young(oop p) {
 939   bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
 940   assert(result == _gens[0]->is_in_reserved(p),
 941          err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, (void*)p));
 942   return result;
 943 }
 944 
 945 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 946 bool GenCollectedHeap::is_in(const void* p) const {
 947   #ifndef ASSERT
 948   guarantee(VerifyBeforeGC   ||
 949             VerifyDuringGC   ||
 950             VerifyBeforeExit ||
 951             PrintAssembly    ||
 952             tty->count() != 0 ||   // already printing
 953             VerifyAfterGC    ||
 954     VMError::fatal_error_in_progress(), "too expensive");
 955 
 956   #endif
 957   // This might be sped up with a cache of the last generation that
 958   // answered yes.
 959   for (int i = 0; i < _n_gens; i++) {
 960     if (_gens[i]->is_in(p)) return true;
 961   }
 962   if (_perm_gen->as_gen()->is_in(p)) return true;
 963   // Otherwise...
 964   return false;
 965 }
 966 
 967 #ifdef ASSERT
 968 // Don't implement this by using is_in_young().  This method is used
 969 // in some cases to check that is_in_young() is correct.
 970 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 971   assert(is_in_reserved(p) || p == NULL,
 972     "Does not work if address is non-null and outside of the heap");
 973   // The order of the generations is young (low addr), old, perm (high addr)
 974   return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
 975 }
 976 #endif
 977 
 978 void GenCollectedHeap::oop_iterate(OopClosure* cl) {
 979   for (int i = 0; i < _n_gens; i++) {
 980     _gens[i]->oop_iterate(cl);
 981   }
 982 }
 983 
 984 void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
 985   for (int i = 0; i < _n_gens; i++) {
 986     _gens[i]->oop_iterate(mr, cl);
 987   }
 988 }
 989 
 990 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 991   for (int i = 0; i < _n_gens; i++) {
 992     _gens[i]->object_iterate(cl);
 993   }
 994   perm_gen()->object_iterate(cl);
 995 }
 996 
 997 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 998   for (int i = 0; i < _n_gens; i++) {
 999     _gens[i]->safe_object_iterate(cl);
1000   }
1001   perm_gen()->safe_object_iterate(cl);
1002 }
1003 
1004 void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1005   for (int i = 0; i < _n_gens; i++) {
1006     _gens[i]->object_iterate_since_last_GC(cl);
1007   }
1008 }
1009 
1010 Space* GenCollectedHeap::space_containing(const void* addr) const {
1011   for (int i = 0; i < _n_gens; i++) {
1012     Space* res = _gens[i]->space_containing(addr);
1013     if (res != NULL) return res;
1014   }
1015   Space* res = perm_gen()->space_containing(addr);
1016   if (res != NULL) return res;
1017   // Otherwise...
1018   assert(false, "Could not find containing space");
1019   return NULL;
1020 }
1021 
1022 
1023 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1024   assert(is_in_reserved(addr), "block_start of address outside of heap");
1025   for (int i = 0; i < _n_gens; i++) {
1026     if (_gens[i]->is_in_reserved(addr)) {
1027       assert(_gens[i]->is_in(addr),
1028              "addr should be in allocated part of generation");
1029       return _gens[i]->block_start(addr);
1030     }
1031   }
1032   if (perm_gen()->is_in_reserved(addr)) {
1033     assert(perm_gen()->is_in(addr),
1034            "addr should be in allocated part of perm gen");
1035     return perm_gen()->block_start(addr);
1036   }
1037   assert(false, "Some generation should contain the address");
1038   return NULL;
1039 }
1040 
1041 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1042   assert(is_in_reserved(addr), "block_size of address outside of heap");
1043   for (int i = 0; i < _n_gens; i++) {
1044     if (_gens[i]->is_in_reserved(addr)) {
1045       assert(_gens[i]->is_in(addr),
1046              "addr should be in allocated part of generation");
1047       return _gens[i]->block_size(addr);
1048     }
1049   }
1050   if (perm_gen()->is_in_reserved(addr)) {
1051     assert(perm_gen()->is_in(addr),
1052            "addr should be in allocated part of perm gen");
1053     return perm_gen()->block_size(addr);
1054   }
1055   assert(false, "Some generation should contain the address");
1056   return 0;
1057 }
1058 
1059 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1060   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1061   assert(block_start(addr) == addr, "addr must be a block start");
1062   for (int i = 0; i < _n_gens; i++) {
1063     if (_gens[i]->is_in_reserved(addr)) {
1064       return _gens[i]->block_is_obj(addr);
1065     }
1066   }
1067   if (perm_gen()->is_in_reserved(addr)) {
1068     return perm_gen()->block_is_obj(addr);
1069   }
1070   assert(false, "Some generation should contain the address");
1071   return false;
1072 }
1073 
1074 bool GenCollectedHeap::supports_tlab_allocation() const {
1075   for (int i = 0; i < _n_gens; i += 1) {
1076     if (_gens[i]->supports_tlab_allocation()) {
1077       return true;
1078     }
1079   }
1080   return false;
1081 }
1082 
1083 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1084   size_t result = 0;
1085   for (int i = 0; i < _n_gens; i += 1) {
1086     if (_gens[i]->supports_tlab_allocation()) {
1087       result += _gens[i]->tlab_capacity();
1088     }
1089   }
1090   return result;
1091 }
1092 
1093 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1094   size_t result = 0;
1095   for (int i = 0; i < _n_gens; i += 1) {
1096     if (_gens[i]->supports_tlab_allocation()) {
1097       result += _gens[i]->unsafe_max_tlab_alloc();
1098     }
1099   }
1100   return result;
1101 }
1102 
1103 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1104   bool gc_overhead_limit_was_exceeded;
1105   return collector_policy()->mem_allocate_work(size /* size */,
1106                                                true /* is_tlab */,
1107                                                &gc_overhead_limit_was_exceeded);
1108 }
1109 
1110 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
1111 // from the list headed by "*prev_ptr".
1112 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1113   bool first = true;
1114   size_t min_size = 0;   // "first" makes this conceptually infinite.
1115   ScratchBlock **smallest_ptr, *smallest;
1116   ScratchBlock  *cur = *prev_ptr;
1117   while (cur) {
1118     assert(*prev_ptr == cur, "just checking");
1119     if (first || cur->num_words < min_size) {
1120       smallest_ptr = prev_ptr;
1121       smallest     = cur;
1122       min_size     = smallest->num_words;
1123       first        = false;
1124     }
1125     prev_ptr = &cur->next;
1126     cur     =  cur->next;
1127   }
1128   smallest      = *smallest_ptr;
1129   *smallest_ptr = smallest->next;
1130   return smallest;
1131 }
1132 
1133 // Sort the scratch block list headed by res into decreasing size order,
1134 // and set "res" to the result.
1135 static void sort_scratch_list(ScratchBlock*& list) {
1136   ScratchBlock* sorted = NULL;
1137   ScratchBlock* unsorted = list;
1138   while (unsorted) {
1139     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1140     smallest->next  = sorted;
1141     sorted          = smallest;
1142   }
1143   list = sorted;
1144 }
1145 
1146 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1147                                                size_t max_alloc_words) {
1148   ScratchBlock* res = NULL;
1149   for (int i = 0; i < _n_gens; i++) {
1150     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1151   }
1152   sort_scratch_list(res);
1153   return res;
1154 }
1155 
1156 void GenCollectedHeap::release_scratch() {
1157   for (int i = 0; i < _n_gens; i++) {
1158     _gens[i]->reset_scratch();
1159   }
1160 }
1161 
1162 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1163   void do_generation(Generation* gen) {
1164     gen->prepare_for_verify();
1165   }
1166 };
1167 
1168 void GenCollectedHeap::prepare_for_verify() {
1169   ensure_parsability(false);        // no need to retire TLABs
1170   GenPrepareForVerifyClosure blk;
1171   generation_iterate(&blk, false);
1172   perm_gen()->prepare_for_verify();
1173 }
1174 
1175 
1176 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1177                                           bool old_to_young) {
1178   if (old_to_young) {
1179     for (int i = _n_gens-1; i >= 0; i--) {
1180       cl->do_generation(_gens[i]);
1181     }
1182   } else {
1183     for (int i = 0; i < _n_gens; i++) {
1184       cl->do_generation(_gens[i]);
1185     }
1186   }
1187 }
1188 
1189 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1190   for (int i = 0; i < _n_gens; i++) {
1191     _gens[i]->space_iterate(cl, true);
1192   }
1193   perm_gen()->space_iterate(cl, true);
1194 }
1195 
1196 bool GenCollectedHeap::is_maximal_no_gc() const {
1197   for (int i = 0; i < _n_gens; i++) {  // skip perm gen
1198     if (!_gens[i]->is_maximal_no_gc()) {
1199       return false;
1200     }
1201   }
1202   return true;
1203 }
1204 
1205 void GenCollectedHeap::save_marks() {
1206   for (int i = 0; i < _n_gens; i++) {
1207     _gens[i]->save_marks();
1208   }
1209   perm_gen()->save_marks();
1210 }
1211 
1212 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
1213   for (int i = 0; i <= collectedGen; i++) {
1214     _gens[i]->compute_new_size();
1215   }
1216 }
1217 
1218 GenCollectedHeap* GenCollectedHeap::heap() {
1219   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1220   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1221   return _gch;
1222 }
1223 
1224 
1225 void GenCollectedHeap::prepare_for_compaction() {
1226   Generation* scanning_gen = _gens[_n_gens-1];
1227   // Start by compacting into same gen.
1228   CompactPoint cp(scanning_gen, NULL, NULL);
1229   while (scanning_gen != NULL) {
1230     scanning_gen->prepare_for_compaction(&cp);
1231     scanning_gen = prev_gen(scanning_gen);
1232   }
1233 }
1234 
1235 GCStats* GenCollectedHeap::gc_stats(int level) const {
1236   return _gens[level]->gc_stats();
1237 }
1238 
1239 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1240   if (!silent) {
1241     gclog_or_tty->print("permgen ");
1242   }
1243   perm_gen()->verify();
1244   for (int i = _n_gens-1; i >= 0; i--) {
1245     Generation* g = _gens[i];
1246     if (!silent) {
1247       gclog_or_tty->print(g->name());
1248       gclog_or_tty->print(" ");
1249     }
1250     g->verify();
1251   }
1252   if (!silent) {
1253     gclog_or_tty->print("remset ");
1254   }
1255   rem_set()->verify();
1256 }
1257 
1258 void GenCollectedHeap::print_on(outputStream* st) const {
1259   for (int i = 0; i < _n_gens; i++) {
1260     _gens[i]->print_on(st);
1261   }
1262   perm_gen()->print_on(st);
1263 }
1264 
1265 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1266   if (workers() != NULL) {
1267     workers()->threads_do(tc);
1268   }
1269 #ifndef SERIALGC
1270   if (UseConcMarkSweepGC) {
1271     ConcurrentMarkSweepThread::threads_do(tc);
1272   }
1273 #endif // SERIALGC
1274 }
1275 
1276 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1277 #ifndef SERIALGC
1278   if (UseParNewGC) {
1279     workers()->print_worker_threads_on(st);
1280   }
1281   if (UseConcMarkSweepGC) {
1282     ConcurrentMarkSweepThread::print_all_on(st);
1283   }
1284 #endif // SERIALGC
1285 }
1286 
1287 void GenCollectedHeap::print_tracing_info() const {
1288   if (TraceGen0Time) {
1289     get_gen(0)->print_summary_info();
1290   }
1291   if (TraceGen1Time) {
1292     get_gen(1)->print_summary_info();
1293   }
1294 }
1295 
1296 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1297   if (PrintGCDetails && Verbose) {
1298     gclog_or_tty->print(" "  SIZE_FORMAT
1299                         "->" SIZE_FORMAT
1300                         "("  SIZE_FORMAT ")",
1301                         prev_used, used(), capacity());
1302   } else {
1303     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1304                         "->" SIZE_FORMAT "K"
1305                         "("  SIZE_FORMAT "K)",
1306                         prev_used / K, used() / K, capacity() / K);
1307   }
1308 }
1309 
1310 //New method to print perm gen info with PrintGCDetails flag
1311 void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
1312   gclog_or_tty->print(", [%s :", perm_gen()->short_name());
1313   perm_gen()->print_heap_change(perm_prev_used);
1314   gclog_or_tty->print("]");
1315 }
1316 
1317 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1318  private:
1319   bool _full;
1320  public:
1321   void do_generation(Generation* gen) {
1322     gen->gc_prologue(_full);
1323   }
1324   GenGCPrologueClosure(bool full) : _full(full) {};
1325 };
1326 
1327 void GenCollectedHeap::gc_prologue(bool full) {
1328   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1329 
1330   always_do_update_barrier = false;
1331   // Fill TLAB's and such
1332   CollectedHeap::accumulate_statistics_all_tlabs();
1333   ensure_parsability(true);   // retire TLABs
1334 
1335   // Call allocation profiler
1336   AllocationProfiler::iterate_since_last_gc();
1337   // Walk generations
1338   GenGCPrologueClosure blk(full);
1339   generation_iterate(&blk, false);  // not old-to-young.
1340   perm_gen()->gc_prologue(full);
1341 };
1342 
1343 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1344  private:
1345   bool _full;
1346  public:
1347   void do_generation(Generation* gen) {
1348     gen->gc_epilogue(_full);
1349   }
1350   GenGCEpilogueClosure(bool full) : _full(full) {};
1351 };
1352 
1353 void GenCollectedHeap::gc_epilogue(bool full) {
1354 #ifdef COMPILER2
1355   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1356   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1357   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1358 #endif /* COMPILER2 */
1359 
1360   resize_all_tlabs();
1361 
1362   GenGCEpilogueClosure blk(full);
1363   generation_iterate(&blk, false);  // not old-to-young.
1364   perm_gen()->gc_epilogue(full);
1365 
1366   if (!CleanChunkPoolAsync) {
1367     Chunk::clean_chunk_pool();
1368   }
1369 
1370   always_do_update_barrier = UseConcMarkSweepGC;
1371 };
1372 
1373 #ifndef PRODUCT
1374 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1375  private:
1376  public:
1377   void do_generation(Generation* gen) {
1378     gen->record_spaces_top();
1379   }
1380 };
1381 
1382 void GenCollectedHeap::record_gen_tops_before_GC() {
1383   if (ZapUnusedHeapArea) {
1384     GenGCSaveTopsBeforeGCClosure blk;
1385     generation_iterate(&blk, false);  // not old-to-young.
1386     perm_gen()->record_spaces_top();
1387   }
1388 }
1389 #endif  // not PRODUCT
1390 
1391 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1392  public:
1393   void do_generation(Generation* gen) {
1394     gen->ensure_parsability();
1395   }
1396 };
1397 
1398 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1399   CollectedHeap::ensure_parsability(retire_tlabs);
1400   GenEnsureParsabilityClosure ep_cl;
1401   generation_iterate(&ep_cl, false);
1402   perm_gen()->ensure_parsability();
1403 }
1404 
1405 oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
1406                                               oop obj,
1407                                               size_t obj_size) {
1408   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1409   HeapWord* result = NULL;
1410 
1411   // First give each higher generation a chance to allocate the promoted object.
1412   Generation* allocator = next_gen(gen);
1413   if (allocator != NULL) {
1414     do {
1415       result = allocator->allocate(obj_size, false);
1416     } while (result == NULL && (allocator = next_gen(allocator)) != NULL);
1417   }
1418 
1419   if (result == NULL) {
1420     // Then give gen and higher generations a chance to expand and allocate the
1421     // object.
1422     do {
1423       result = gen->expand_and_allocate(obj_size, false);
1424     } while (result == NULL && (gen = next_gen(gen)) != NULL);
1425   }
1426 
1427   if (result != NULL) {
1428     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1429   }
1430   return oop(result);
1431 }
1432 
1433 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1434   jlong _time;   // in ms
1435   jlong _now;    // in ms
1436 
1437  public:
1438   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1439 
1440   jlong time() { return _time; }
1441 
1442   void do_generation(Generation* gen) {
1443     _time = MIN2(_time, gen->time_of_last_gc(_now));
1444   }
1445 };
1446 
1447 jlong GenCollectedHeap::millis_since_last_gc() {
1448   // We need a monotonically non-deccreasing time in ms but
1449   // os::javaTimeMillis() does not guarantee monotonicity.
1450   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1451   GenTimeOfLastGCClosure tolgc_cl(now);
1452   // iterate over generations getting the oldest
1453   // time that a generation was collected
1454   generation_iterate(&tolgc_cl, false);
1455   tolgc_cl.do_generation(perm_gen());
1456 
1457   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1458   // provided the underlying platform provides such a time source
1459   // (and it is bug free). So we still have to guard against getting
1460   // back a time later than 'now'.
1461   jlong retVal = now - tolgc_cl.time();
1462   if (retVal < 0) {
1463     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, retVal);)
1464     return 0;
1465   }
1466   return retVal;
1467 }
--- EOF ---